Apparatus for developing differential pressures in a conduit line

ABSTRACT

A venturi in a conduit line serves to create pressure differences which indicate the rate of flow of a gaseous medium. The pressure difference is employed to control the volume of steam that is added to the combustion zone for the gaseous medium. The apparatus includes means for relieving pressure upstream of the venturi.

United States Patent [54] APPARATUS FOR DEVELOPING DIFFERENTIAL PRESSURES IN A CONDUIT LINE 3 Claims, 4 Drawing Figs.

[52] U.S. Cl 137/599.l, 110/161, 137/98 [51] Int. Cl F23l 13/00 [50] v Field ofSearch 98/78;

[56] References Cited UNITED STATES PATENTS 2,562,507 7/1951 Pierce 137/93X 3,188,055 6/1965 Lutjens l37/599X FOREIGN PATENTS 699,316 11/1953 Great Britain 137/599 Primary Examiner-Robert G. Nilson AttorneyLloyd P. Shank ABSTRACT: A venturi in a conduit line serves to create pressure differences which indicate the rate of flow of a gaseous medium. The pressure difference is employed to control the volume of steam that is added to the combustion zone for the gaseous medium. The apparatus includes means for relieving 100, 101,11 pressure upstream of the venturi.'

/4\ i h 56 C D Q M u 52 47 24 AZ 2! n F I} 3 22 6 i 26 l 46 15 38 I9 1&1 ale :5; 2.9

Patented March, 16, 1971 3,570,535

/4\ F/GJ K H P n 48 7 47 i-"fig MN I 2 g 3 /i 2 V :l H I 3 3 22 /\6 46 EH5 38 26 l9 irlie;

Jomv SMITH Z/NK ROBERT D. REED HAROLD E KOO/V8 ATTORNEY APPARATUS FOR DEVELOPING DIFFERENTIAL PRESSURES IN A CUNDUIT LINE The present invention relates to apparatus for developing differential pressures as a result of the flow of gas in a conduit line with the pressure difference serving to indicate the rate of flow of gas and the invention more particularly pertains to means which serves to divert some of the gas from the venturi when the pressure in the conduit line upstream of the venturi attains an undesired level.

Apparatus for developing differential pressures in a conduit line have been known and serve as flow sensors with the pressure differences being utilized to actuate controls for the admission of steam to the combustion zone of a flare stack to suppress smoke. A requirement for the control of the admission of steam for the combustion zone is that when the velocity of the dump gas attains a flow rate of about l /feet per second steam should be admitted for suppressing smoke in the combustion zone. The quantity of steam admitted to the combustion zone should be linear with the increment increases in the flow of the dump gases. In a prior arrangement, a venturi has been employed in the conduit line supplying the dump gas to a flare stack to develop differential pressures which have been utilized for the control of the admission of steam to the combustion zone of the flare stack. Such equipment is satisfactory except when the rate of flow of the dump gases exceeds a normal flow rate, the pressure upstream of the venturi increases and often becomes excessive.

It is an object of the present invention to provide apparatus for developing differential pressures in a conduit line leading to a flare stack so that such pressure differences may be used to control the admission of steam to the combustion zone of a flare stack and to provide means for relieving the pressure within the conduit line upstream of the apparatus.

Other objects and features of the invention will be appreciated and become apparent to those skilled in the art to which the invention pertains and asthe present disclosure proceeds, and upon consideration of the following detailed description taken in conjunction with the annexed drawings wherein an embodiment of the invention is disclosed.

In the drawings:

FIG. 1 is a side elevation with a portion of apparatus embodying the invention shown in section and on the line 1-1 of FIG. 2.

FIG. 2 is a sectional plan view on a larger scale and taken on the line 2-2 of FIG. 1.

FIG. 3 is a sectional view of the venturi and showing a low pressure probe in association therewith.

FIG. 4 is a fragmentary sectional view of a portion of the poppet valve.

The invention is directed to apparatus for controlling the volume of steam supplied by a pipeline 10 to a manifold 11 associated with a flare stack 12. The steam is discharged from the manifold through nozzles 14 to suppress smoke in the combustion zone at the upper end of the stack 12. The dump gases are supplied into the lower end of the flare stack through a conduit line 16. The steam is desirably admitted to the manifold 11 at a rate which is linear with respect to the increases in the flow of the dump gas through the conduit line 16.

The invention pertains to apparatus indicated at 18 incorporated in the conduit line 16. This apparatus is equipped with an inlet conduit fitting 19 and an outlet conduit fitting 21 for connection to flanged sections of the conduit line 16 and through which the dump gas is supplied into the flare stack 12. The apparatus includes a housing 22 of cylindrical formation which is closed at its lower end by a bottom wall 23 and closed at its upper end by a top wall 24. The conduit fittings 19 and 21 extend through diametrically opposite portions of the housing 22 and are sealed with respect thereto.

The inlet conduit fitting 19 extends within the housing 18 and is equipped at its inner end with a short vertically disposed conduit element 26. A tubular member 28 is mounted in the cylindrical wall of the conduit element 26 as best shown in FIG. 2. A butterfly valve 29 mounted on a shaft 31 is adapted to control theopen area within the tubular member 28. The shaft 31 extends outside the housing 18 so that the position of the butterfly valve 29 may be adjusted.

A flange 33 is carried by the upper end of the conduit element 26. A poppet valve 34 of a selected weight is adapted to overlie the flange 33 and substantially obstruct the upper end of the conduit element 26. Spacer elements 36 (FIG. 4) of selected dimensions provide a calculated minimum gas flow passage area at the perimeter of the conduit element 26 when the poppet valve 34 is in its lowermost position. The poppet valve is guided for vertical movements by a stem 37 which depends in a guide tube 38 and which is supported by the bottom wall 23. The stem 37 desirably extends through the bottom wall 23 so that force may, be applied to the stem 37 to manually raise the poppet valve.

An opening 40 is provided in the conduit fitting 19 and pipe fittings 41 extend therefrom and provide a bypass which includes a venturi 42 as shown in FIG. 2. The downstream end portion of the venturi is connected with pipe fittings 43 to be in communication with the interior of the housing 22 at 45 as shown in FIG. 1 and upstream of the poppet valve 34.

A high pressure tap 46 in communication with the interior of the conduit fitting 19 upstream of the poppet valve is connected by tubing 47 to a differential pressure sensing device 48. A low pressure tap provided at the throat of the venturi 42 is connected to the differential pressure sensing device by tubing 52. The differential pressure sensing device may be of any suitable type and includes means for adjusting the position of the valve 56 in the steam line 10 in response to the rate of flow of gas through the conduit line 16.

In operation, the dump gas moves into the housing 22' through the conduit fitting 19 and escapes through the outlet conduit fitting 21 when the rate of flow is normal and when the butterfly valve 29 is in an open position. By adjusting the position of the butterfly valve 29, the pressure within the chamber 15 upstream of the poppet valve 34 is increased and the pressure therein is greater than the pressure within the chamber 20 downstream of the poppet valve 34. There is a flow of some of the dump gas through the venturi 42 and the acceleration of the gas in moving through the venturi provides a pressure lower at the throat than the pressure within the chamber 15. Thus the differences in these pressures serve to actuate the pressure sensing device 48 which functions cause the valve 56 to move towards an open position as the difference in the pressures increases.

lt'will be noted that the total area of the outlet conduit fitting 21 and the minimum space between the poppet valve 34 and the flange 33 and the open area of the venturi represents a total area which is less than the area of the conduit fitting 19 so that the pressure in the chamber 15 is greater than the pressure in the chamber 20 at any condition of flow of gas in the conduit line. The minimum flow of the gas through the poppet valve 34 is determined by its weight and by the dimensions of the spacer elements 36. The open area between the poppet valve 34 and the flange 33 and the weight of the poppet valve are so dimensioned and proportioned that the poppet valve 34 remains in the position shown in FIG. 2 under normal gas flow to the flare stack. The weight of the poppet valve may be altered to provide relief when the pressure in the chamber 15 attains any desired level.

While the invention has been described with regard to one type of apparatus and one overall assembly, it will be appreciated that changes may be made in the elements as well as in the overall organization. Such modifications and others may be made without departing from the spirit and scope of the invention.

We claim:

I. In apparatus for developing differential pressures in a conduit line, a housing, an outlet conduit fitting carried by said housing for connection to the conduit line, an inlet cohduit fitting carried by said housing for connection to said conduit line, a conduit element within said housing joining said inlet conduit fitting, said conduit element having a vertically disposed outlet opening within said housing, a weighted poppet valve for obstructing said outlet opening, said conduit element having an opening therethrough upstream of said poppet valve providing a passage from the inlet conduit fitting to the outlet conduit fitting, means for varying the area of said passage, and a Venturi connected between spaced points of said inlet conduit fitting. 

1. In apparatus for developing differential pressures in a conduit line, a housing, an outlet conduit fitting carried by said housing for connection to the conduit line, an inlet conduit fitting carried by said housing for connection to said conduit line, a conduit element within said housing joining said inlet conduit fitting, said conduit element having a vertically disposed outlet opening within said housing, a weighted poppet valve for obstructing said outlet opening, said conduit element having an opening therethrough upstream of said poppet valve providing a passage from the inlet conduit fitting to the outlet conduit fitting, means for varying the area of said passage, and a Venturi connected between spaced points of said inlet conduit fitting.
 2. In apparatus for developing differential pressures in a conduit line according to claim 1, wherein the means for varying the area of the passage comprises a butterfly valve.
 3. In apparatus for developing differential pressures in a conduit line according to claim 1 wherein the spacer elements provide a minimum open area between the poppet valve and said conduit element. 